People with a history of the digestive disorder celiac disease are three
times more likely to develop schizophrenia than those without the disease,
according to a report by Danish researchers and a researcher at the Johns
Hopkins Bloomberg School of Public Health. The report is published in
the February 21, 2004, edition of the British Medical Journal.

Celiac disease is an autoimmune disorder that impairs the body's ability
to digest the protein gluten, which is found in grains and many other
foods. The condition can lead to diarrhea, weight loss and malnutrition.
William W. Eaton, PhD, lead author of the report and interim chair of
the Department of Mental Health at the School of Public Health, said,
"For years, scientists have suspected a link between celiac disease
and schizophrenia. Our research shows that the link is moderately strong."

Dr. Eaton and his colleagues examined the records of 7,997 schizophrenic
patients admitted to a Danish psychiatric facility for the first time
between 1981 and 1998. Those records were compared to Denmark's national
patient register to determine if the schizophrenic patients or their parents
were previously treated for celiac disease. The researchers also looked
for diagnosis of similar digestive disorders not previously associated
with schizophrenia, which included dermatitis herpetiformis, Crohn's disease
and ulcerative colitis.

The researchers found a small number of schizophrenic patients were previously
treated for celiac disease or had a parent treated for celiac disease.
Both conditions are rare. The prevalence of celiac disease among schizophrenics
was 1.5 cases per 1,000 compared to 0.5 cases per 1,000 in the larger
control group. After adjusting for other factors associated with schizophrenia,
the researchers determined that the risk of schizophrenia was three times
greater with a history of celiac disease. Crohn's disease and ulcerative
colitis were not associated with an increased risk of schizophrenia.

"More research is needed to understand the link between celiac disease
and schizophrenia. The most important question is whether treatment for
celiac disease, in the form of a gluten-free diet, would benefit the small
proportion of individuals with schizophrenia who are genetically prone
to celiac disease but have not been diagnosed with it," said Dr.
Eaton.

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"Coeliac disease and schizophrenia: population based case control
study with linkage of Danish national registers" was written by William
W. Eaton, Preben Bo Mortensen, Esben Agerbo, Majella Byrne, Ole Mors and
Henrik Ewald. Mortensen, Agerbo and Byrne are with the National Centre
for Register-Based Research, Aarhus University, Denmark. Mors and Ewald
are with the Institute of Basic Psychiatric Research, Aarhus, Denmark.

The research was funded by the Danish National Research Foundation, Stanley
Medical Research Institute and the National Institute for Mental Health.